Here's how I have used the upgrade vouchers, free companion pass and points in the past. Booked myself full fare biz ticket. Used the free companion ticket so my wife could travel with me....just paid the taxes for her. Then used 12000 GC points for my 2 kids for Econ return...just paid the taxes for them. Finally, used my 4 upgrade vouchers to upgrade the kids. It all worked out fine but admittedly I booked it well in advance.

I should also mention that once well all biz seats were sold I had to book Econ to ORD. However, I requested an upgrade when I checked in just in case of a no show and was lucky enough to be upgraded at the boarding gate. The staff were great.

Finally, I have called as late as the day before travelling on 2 occasions to use my vouchers to request upgrades for friends on the same flight and these worked out fine. In my experience EI treat their Elites well when it comes to using the vouchers.